Read Dharma Mittra's response:
Over the years, I have seen many of my students become teachers and experience the problems you are dealing with now. I will tell you what I have told them:
The highest type of all charities and dharma (duty) is the sharing of spiritual knowledge. If you are teaching asanas, Pranayamas, and meditation without a foundation in the ethical disciplines, such as the yamas (moral commandments), niyamas (rules of conduct or observances), and self-knowledge, it will eventually become boring for both you and your students.
To keep this from happening, it is of utmost importance that you continue your own growth in practice and strive to purify your mind. Evoke sattvic, or pure, thoughts and aim to cleanse the gross physical body and the subtle astral body (the body of consciousness and thought) of toxics. Also helpful in inducing a state of sattva is following a light, healthy vegetarian diet. You will immediately feel better and more inspired. And of utmost importance is the practice of right conduct toward oneself and toward others, through living according to the yamas and niyamas.
Ultimately, sattva comes from knowledge of the self, which you can achieve by understanding karma and reincarnation, relinquishing the ego, and letting go of attachments. When one is in this state there is no feeling of emptiness or boredom.
Remember, though, that the mental knowledge of these things is not enough. You must also practice silent meditation regularly to become calm and peaceful in order to personally realize that knowledge. The goal of yoga is knowledge, specifically knowledge that leads to self-realization established in sattva, or a state of bliss. Once you are firmly established in sattva, you will be able to share your spiritual experience and encourage your students to seek enlightenment as well.
Sri Dharma Mittra, who has been teaching since 1967, was the first independent yoga teacher in New York City. In 1984, he created the famous Master Yoga Chart of 908 Postures, which has become an invaluable teaching tool. Dharma is the creator of more than 300 postures and is the author of the book Asanas: 608 Yoga Poses. He is also the inspiration for the Yoga Journal coffee-table book Yoga. His Maha Sadhana DVD set (A Shortcut to Immortality, for Level I, and Stairway to Bliss, for Level II), has been widely acclaimed as preservations of the main teachings of yoga. Dharma Mittra: A Friend to All, is a biography documenting experiences of his students from the 1960s on. Dharma Mittra: Yoga Life of a Yogi teacher trainings (200- and 500-hour) are held in New York, San Francisco, Japan, and at workshops worldwide. For more information, visit www.dharmayogacenter.com.